Locking mechanism for miter saw with hinge linkage linear guide

ABSTRACT

A power saw includes a table configured to receive a workpiece, a saw blade and motor assembly, and a linear guide mechanism operatively connected to the table and being configured to pivotally support the saw blade and motor assembly. The linear guide mechanism enables movement of the saw blade and motor assembly along a predetermined linear path in a forward or a rearward direction at a constant level, and includes a first link and a second link pivotally connected by a first hinge connection. The first and second links enable the linear guide mechanism to maintain the saw blade and motor assembly at the constant level. The power saw further includes a locking mechanism which is fixed to the first hinge connection for locking the linear guide mechanism to prevent the saw blade and motor assembly from being moved along the predetermined linear path.

This patent is a continuation-in-part of U.S. application Ser. No.12/797,043 filed Jun. 9, 2010, which issued on Dec. 4, 2012 as U.S. Pat.No. 8,322,261.

BACKGROUND OF THE INVENTION

This patent generally relates to power miter and abrasive cut off saws.

Miter saws have been the subject of continued research and developmentefforts in the power tool arena for decades, and many improvements havebeen made that has resulted in increased ease of use and productivity.Artisans who install trim carpentry have used power miter saws for sometime and it is well known that wide stock such as crown molding and thelike often requires a miter saw with either a bigger saw blade or aconfiguration that enables the blade to be moved along a horizontal pathaway and toward the fence of the miter saw. Such blade movingconfigurations are generally marketed as sliding compound miter saws,principally because most if not all commercially available saws of thistype have a sliding guide assembly comprised of elongated rods thatslide in respective bushings to move the saw blade and motor assemblyrelative to the fence of the saw.

Such sliding guide assemblies are an expensive component of such mitersaws. The current state of the art for such sliding miter saws includesa linear guide that typically consists of two of such bushings and rodcombinations. These relatively expensive linear bearings consist ofrecirculating ball bearings that operate together with turned, ground,polished and hardened steel rods that are approximately 40 cm long and30 mm in diameter. To have minimum play and deflection of the saw bladeand motor assembly, precise fits are required between the rods and thelinear recirculating ball bearings over the entire linear travel of therods. The rod must be made of a high hardness steel to preventindentation by the hard steel balls. Such construction is relativelyexpensive.

Additionally, an undesirable feature of such bushing and rod linearguides is that space must be provided behind the saw for the rods toextend when the saw blade is positioned near the fence. Because of thisspace requirement, such a sliding saw cannot be put next to a wall whichresults in a larger footprint being occupied by such a saw.Additionally, these bushings and rod linear guide mechanisms aresusceptible to damage from dirt and grit, particularly if the saw is asliding abrasive cut off saw where an abrasive wheel is used to cutsteel and other materials. The abrasive wheel grinds its way through thesteel and produces a considerable volume of abrasive particles thatgenerally come out of the back of the saw. These abrasive particles canpenetrate into the ball bushings and damage the bearing. While it ispossible to cover the rods with a bellows or similar cover, the hostileenvironment generally leads to degradation of the fabric and penetrationof the ball bushing by the abrasive particles.

There is a continuing need for improvement in the design and developmentof miter and cut-off saws that have linear guide assemblies.

SUMMARY OF THE INVENTION

This patent relates to various embodiments of a power saw having a tableconfigured to receive a workpiece, a saw blade and motor assembly, and alinear guide mechanism operatively connected to the table and beingconfigured to pivotally support the saw blade and motor assembly. Thelinear guide mechanism enables movement of the saw blade and motorassembly along a predetermined linear path in a forward or a rearwarddirection at a constant level, and includes a first link and a secondlink pivotally connected by a first hinge connection. The first andsecond links enable the linear guide mechanism to maintain the saw bladeand motor assembly at the constant level. The power saw further includesa locking mechanism which is fixed to the first hinge connection forlocking the linear guide mechanism to prevent the saw blade and motorassembly from being moved along the predetermined linear path.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a right side perspective view of a first preferred embodimentof the present invention, particularly illustrating the saw blade beinglocated in the extended position away from the fence;

FIG. 2 is a right side perspective view of the embodiment shown in FIG.1, but illustrating the saw blade in a position near the fence;

FIG. 3 is a side elevation of the embodiment shown in FIG. 1 with thesaw blade in the extended position away from the fence;

FIG. 4 is a rear view of the embodiment shown in FIG. 1, with the sawblade away from the fence;

FIG. 5 is a right front perspective view of a second preferredembodiment of the present invention, particularly illustrating the sawblade being located in the extended position away from the fence;

FIG. 6 is a right front perspective view of the embodiment shown in FIG.5, but illustrating the saw blade in a position near the fence;

FIG. 7 is a side elevation of the embodiment shown in FIG. 5 butillustrating the saw blade in a position near the fence;

FIG. 8 is a rear view of the embodiment shown in FIG. 5, with the sawblade in a position away from the fence;

FIG. 9 is a third preferred embodiment of the present invention,particularly illustrating the saw blade being located in the extendedposition away from the fence;

FIG. 10 is a side elevation of the embodiment shown in FIG. 9 with thesaw blade in the extended position away from the fence.

FIG. 11 is another side elevation of the embodiment shown in FIG. 9,with the saw blade near the fence;

FIG. 12 is a rear view of the embodiment shown in FIG. 9, with the sawblade located away the fence;

FIG. 13 is a perspective view of the right side of a miter saw, with theblade and motor assembly in an extended and lowered position, inaccordance with another embodiment of the invention;

FIG. 14 is a perspective view of the right side of the miter saw shownin FIG. 13, with the blade and motor assembly in a retracted and loweredposition;

FIG. 15 is a perspective view of the left side of the miter saw shown inFIG. 13, with the blade and motor assembly in an extended position;

FIG. 16 is a perspective view of the left side of the miter saw shown inFIG. 13, with the blade and motor assembly in the retracted and loweredposition;

FIG. 17 is a top plan view of the miter saw shown in FIG. 13, with theblade and motor assembly in the retracted and lowered position and theblade being perpendicular to the fence;

FIG. 18 is a top plan view of the miter saw shown if FIG. 13, with theblade and motor assembly in the retracted and lowered position and theblade being at a miter angle to the fence;

FIG. 19 is a is a perspective view of the left side of the miter sawshown in FIG. 13, with the blade and motor assembly beveled to the leftside;

FIG. 20 is a sectional view of a locking mechanism in accordance withone embodiment of the invention, shown in a locked position;

FIG. 21 is a sectional view of the locking mechanism shown in FIG. 20 inan unlocked position;

FIG. 22 is top plan view of the locking mechanism of FIG. 20 shown in alocked position when the blade and motor assembly is in a fullyretracted position;

FIG. 23 is top plan view of the locking mechanism of FIG. 20 shown in alocked position when the blade and motor assembly is in a fully extendedposition;

FIG. 24 is a perspective view of the locking mechanism of FIG. 20 shownin an unlocked position when the blade and motor assembly is in a fullyretracted position;

FIG. 25 is a perspective view of the locking mechanism of FIG. 20 shownin a locked position when the blade and motor assembly is in a fullyretracted position;

FIG. 26 is a perspective view of the locking mechanism of FIG. 20 shownin a locked position when the blade and motor assembly is in a fullyextended position; and

FIG. 27 is a perspective view of the locking mechanism of FIG. 20 shownin an locked position when the blade and motor assembly is in a fullyextended position.

DETAILED DESCRIPTION

Various different embodiments of the miter saws are shown and describedherein, with the each of the embodiments having a multiple hinge linkagethat is designated herein as a horizontal hinge linkage thatinterconnects the saw blade and motor assembly to the table of the mitersaw. It should be understood that while it is referred to herein as agenerally horizontal hinge linkage, the several shafts of the linkagemay not always be exactly horizontal, and may have a pivot axis that canvary up to about 30 degrees in either direction from exact horizontal.However, it is preferred that the axes be in a substantially horizontalorientation when the saw is set at a zero degree bevel position.Regardless of the bevel angle or the orientation of the surface on whichthe saw is supported, the shafts are preferably substantially parallelto the arbor shaft in which the blade is mounted and thereforesubstantially perpendicular to the plane of the saw blade.

The horizontal hinge linkage is utilized rather than an elongated rodand bushing configuration and provides increased stiffness to undesiredmovement of the saw blade arising from structural deflections duringcutting operations. Some of the embodiments also have a vertical hingelinkage for maintaining the elevation of the saw pivot head (to whichthe saw blade and motor assembly is attached) constant during movementof the saw blade and motor assembly away and toward the fence during acutting operation. One of the described embodiments utilizes thehorizontal hinge linkage together with a single rod and bushingarrangement whereby the rod and bushing arrangement also maintains aconstant elevation of the saw pivot head as the saw blade and motorassembly is moved toward and away from the fence during a cuttingoperation. It should be understood that the saw blade and motor assemblyis pivotable about a saw pivot that is part of the saw pivot head, whichis attached to the horizontal hinge linkage. The saw blade and motorassembly can be pivoted up out of contact with a work piece or moveddown into contact with a work piece during a cutting operation as isconventional for miter saws.

Such hinge linkages have a cost advantage compared to conventionalbushing and rod guides because they have a simpler construction, whichmay comprise as few as two generally planar shaped linkages that areconnected together by shafts that may preferably incorporate rotarybushings or low cost ball bearings and which are also linked to thesupport frame of the rotatable table as well as to the saw pivot head.Tight tolerance fits between hinge components are relatively easier toachieve using low cost ball bearings that are preloaded in the axialdirection so that nearly all axial and radial play is removed. Incontrast, conventional bushings and sliding rod systems requireexpensive manufacturing processes to ensure that the outside surface ofthe rod is precise over its entire length. Another advantage of the useof hinge linkages is that their stiffness characteristics are determinedprimarily from the width of the hinge linkages as measured along thepivot, i.e., shaft axis. Thus, increased system stiffness can beachieved by making the hinge larger and this is generally less expensivethan using larger rods and bushings.

As previously mentioned, the horizontal hinge linkage pivots around axesthat are perpendicular to the cutting plane of the blade and thereforeprovides increased stiffness along the axis of rotation of the saw bladeand because of this desirable characteristic, the length of the hingeshafts is greater than other shaft lengths such as those used in thevertical hinge linkage. The structural stiffness is very important tothe quality of cuts made by the saw. Without the requisite structuralstiffness, it is common for the saw blade to deflect out of the desiredcutting plane on an intermittent basis which can result in one or morecut discontinuities or jagged cut portions, rather than a continuoussmooth cut at the desired angle.

Another advantage of the hinge linkage is that it has greatly reducedsensitivity to dirt and grit because the bearing surfaces of a hingelinkage are not exposed but are contained within a ball bearing or shortrotary bushing. Such ball bearing or rotary bushings can be relativelyeasily sealed compared to a rod and bushing system where the entire rodis a critical bearing surface and therefore has to be sealed with alarge accordion or bellow shaped fabric or other type of cover which isoften easily damaged.

Turning now to the first preferred embodiment shown in FIGS. 1-4, themiter saw, indicated generally at 10, has a generally circular base 12with an attached fence 14, which base supports a rotatable table 16 thathas a miter arm control assembly, indicated generally at 18, foradjusting the rotational position of the table for setting the miterangle of work piece that would be placed on the table 16. A saw bladeand motor assembly, indicated generally at 20, is operatively connectedto the table 16 by a linear guide mechanism, indicated generally at 22.The saw blade and motor assembly 20 has an electric motor 24 that isoperatively connected through a belt and gear mechanism, not shown butlocated within housing portion 26 that drives a saw blade 28. A handle30 enables an operator to move the blade and motor assembly 20 into andout of engagement with a work piece that may be placed on the table 16adjacent the fence 14. The blade and motor assembly 20 is pivotableabout a saw pivot shaft 32 that is connected to a saw pivot head 34 towhich the linear guide mechanism 22 is attached. The blade and motorassembly 20 is shown in FIG. 1 to be in a position where the blade ismoved to its extended position away from the fence 14 and lowered intocutting position where a workpiece is placed on the table 16. Duringoperation, an operator places a work piece on the table 16, brings thehandle 30 down into cutting position either before or after activatingthe motor 24 and then pushes the handle 30 toward the fence 14 to havethe blade 28 cut the workpiece. At the end of the cut, the blade andmotor assembly 20 would be essentially in the position shown in FIG. 2where the bottom reach of the blade 28 is generally coextensive with thefence 14.

The linear guide mechanism 22 of the first preferred embodiment shown inFIGS. 1-4 is designed so that the miter saw has a dual bevel operation,rather than a single bevel operation, meaning that the bevel angle canbe adjusted either right or left from the normal zero angle or positionwherein the plane of the blade 28 is perpendicular to the plane of thetop surface of the table 16. The blade and motor assembly 20 as well asthe linear guide mechanism and rotate about a bevel pivot shaft 36, withthe linear guide mechanism having a support frame 38 with a generallycylindrical end portion 40 to which the bevel pivot shaft 36 isconnected to. The shaft 36 extends through an opening in an enlargedextension 42 of the table 16. Thus, the end portion 40 can rotaterelative to the extension 42 and be supported by the shaft 36. Thesupport frame 38 is preferably a casting that has a lower flange 44, anupper flange 46 as well as vertically oriented flanges 48 and 50.

A horizontal hinge linkage is comprised of links 52 and 54 which haveadjacent ends connected together by a shaft 56. The saw pivot head 34has a pair of spaced flanges 58 as well as a single flange 60 locatedbelow the flanges 58. The link 54 has its opposite end connected to theflanges 58 by a shaft 62. Similarly, the opposite end of the link 52 isconnected to the vertical flanges 48 and 50 by a shaft 64. As previouslymentioned and while not specifically illustrated, the shafts 32, 62, 56,64, 78 and 82 are preferably of the type which utilize rotary bushingsor low cost ball bearings so that they are freely rotatable and willhave an extended useful life.

As is best shown in FIGS. 1 and 2, the link 52 has a generally L-shapedside configuration with the transverse extension 66 having the aperturein which the shaft 56 is located. This permits the two links 52 and 54to be folded together in a generally parallel arrangement as shown inFIG. 2 when the blade and motor assembly 20 is moved into its finalcutting position where the blade is adjacent to the fence 14. As is bestshown in FIG. 4, the width of the links 52 and 54 is relatively largeand therefore the shafts 56, 62 and 64 that interconnect the links 52and 54 with one another and with the saw pivot head 34 and support frame38 are relatively long. This contributes to the desirable stiffness ofthe linear guide mechanism which substantially reduces, if noteliminates, any movement by the blade out of the cutting plane which canresult in poor quality cutting. Stated in other words, the extremelywide links and their coupling to the saw pivot head and support frame 38results in high rigidity reducing torsional and linear deflection of thesaw blade away from its intended cutting plane which is very desirablefrom a cut quality standpoint.

As best shown in FIG. 4, the link 52 is not a solid construction, buthas side walls 68 and end walls 70 with cross braces 72 provided toprovide increased overall strength for the link. The link 54 issimilarly constructed as is shown in FIG. 1, it also having similarlyconfigured side walls, end walls and cross braces. The hinge links 52and 54 are preferably die cast aluminum but can be steel stamping ifdesired.

The vertical hinge linkage is located below the horizontal hinge linkageand it comprises links 74 and 76 which have adjacent ends connectedtogether by a vertical shaft 78. The links 74 and 76 are not as wide asthe horizontal hinge links 52 and 54 for the reason that theirfunctionality is to maintain the elevation of the saw pivot head 34constant during movement of the blade and motor assembly 20 toward andaway from the fence 14. Elevational deflections are not as critical fora miter saw cut quality for the reason that the work piece is generallybeing completely cut through.

The narrower links 74 and 76 are vertically displaced from one anotherwhich requires the elongated vertical shaft 78 to extend to interconnectthem. The link 74 is located between the horizontal flanges 44 and 46and is pivotally connected to these flanges by a shaft 80. Similarly,the link 76 has spaced flange portions that are connected to the flange60 by a shaft 82. As is shown in FIG. 1, the flange 60 is locatedbeneath the near flange 58 and the flanges 44 and 46 are also locatedbeneath the vertical flanges 48 and 50, and the shaft 78 thatinterconnects the links 74 and 76 extends away or to the left side ofthe saw (as viewed from the handle 30) so that when the vertical andhorizontal linkages are folded together as shown in FIG. 2, little ifany portion of the links extend outside of the width of the flanges 48and 50. This is significant in that changing of the bevel angle of theblade and motor assembly 20 can be accomplished in either the left orthe right direction and the hinge linkages will not interfere with thedual bevel adjusting capability.

It should also be apparent from FIG. 2 that when the blade and motorassembly 20 are moved as far toward the fence 14 as is possible, thelinkages do not extend in any rearward direction beyond the originalposition end of the support frame 38. This enables the miter saw to beplaced near a wall, for example, and be fully operational, unlike manyconventional sliding rod and bushing configurations of compound mitersaws.

A second preferred embodiment is shown in FIGS. 5-8 and have manysimilar components as the embodiment shown in FIGS. 1-4. In thefollowing description, components that are labeled with the same numbersas those shown and described with regard to the first preferredembodiment are substantially similar in their design, configuration andoperation and therefore will not be described in detail. Components withreference numbers having a prime or double prime designation are similarto those that are identified with regard to the embodiment shown inFIGS. 1-4, but may have some structural differences which are apparentor which will be generally described or which will be given differentnumbers than those illustrated in FIGS. 1-4.

The second preferred embodiment is indicated generally at 100 in FIGS.5-8 and has many similarities to the first preferred embodiment, butwhile the first embodiment is a dual bevel configuration saw, the secondembodiment saw 100 is a single bevel configuration. The links 74′ and76′ are connected together by a shaft 78′ that is not as long as theshaft 78 of the first preferred embodiment, because the links 74′ and76′ are vertically adjacent one another rather than being spaced apart.Also, the link 76′ is at an elevation that is substantially similar tothe elevation of the link 54′ and therefore unable to fold toward thelink 52″ and 54′. Thus, the connection between link 74′ and 76′ extendsoutwardly away from the links 52′ and 54′. Because of the outwardextension, particularly when it is folded as shown in FIGS. 6 and 8, thelinks interfere with other portions of the saw 100 when the saw would bepivoted in the counterclockwise direction as shown in FIG. 8. Therefore,the single bevel operation of this second preferred embodiment is in theclockwise direction as shown in FIG. 8.

A third preferred embodiment of the invention is the saw 110 that isshown in FIGS. 9-12 is less detail than the embodiments of FIGS. 1-8.Saw 110 has a horizontal hinge linkage comprising links 52″ and 54″ thatare interconnected and operate substantially similar to those describedin the embodiments of FIGS. 1-8. The saw pivot head 34″ has a slightlydifferent configuration and the end of the link 54″ is connected to thesaw pivot shaft 32 which is also journaled in the saw pivot head 34″. Anelongated rod 112 is journaled in a bushing (not shown but located inthe upper end of support frame 38) and maintains the saw pivot head 34″at a constant elevation as the blade and motor assembly 22 moves theblade 28 toward the fence 14. Only one rod 112 is provided for thereason that control of the saw blade cutting plane is provided by thehorizontal hinge linkage, as is the case with the other embodimentsshown in FIGS. 1-8, and the only function that is performed by the rod112 is to keep the pivot head 34″ at a constant elevation duringoperation. In this regard, the blade and motor assembly 20 is shown inits retracted position in FIGS. 9 and 10 and in the cutting position inFIG. 11 where the blade 28 is adjacent the fence 14. In the positionshown in FIG. 11, it is apparent that the rod 112 will extend beyond therear surface of the support frame 38″ which requires a larger footprintin that it would not be possible to place the saw 110 with the supportframe 38″ located close to a wall or other similar surface. Thus, whilethis embodiment does not have the space advantages of the first andsecond preferred embodiments, this embodiment has the advantage ofcontrolling the saw blade cutting plane by a generally horizontal hingeas is achieved in all embodiments and only one rod and bushingcombination is required which provides a cost benefit compared toconventional arrangements which have a pair of rod and bushingconfigurations.

In accordance with another embodiment of the invention, a miter saw isshown in FIGS. 13-19 and is indicated generally at 200. This embodimentis also described in related U.S. application Ser. No. 13/194,705, whichis hereby incorporated by reference it its entirety. Many of thecomponents are similar to the first embodiment 10 so that wherereference numbers are the same as the description of the FIG. 1, suchcomponents and their functionality are very similar, if not identical.Components with reference numbers above 200 are sufficiently differentfrom analogous components of the other embodiments to warrant separatenumbers or are new in the fourth embodiment.

Turning to FIGS. 13 and 14, a miter saw 200 also has a generallycircular base 12 with an attached fence 14. The base 12 supports arotatable table 16 that has a miter arm control assembly, indicatedgenerally at 18, for adjusting the rotational position of the table forsetting the miter angle of a workpiece that would be placed on thetable. A saw blade and motor assembly, indicated generally at 20, isoperatively connected to the table 16 by a linear guide mechanism,indicated generally at 202. The saw blade and motor assembly 20 has anelectric motor 24 that is operably connected through a belt and gearmechanism (not shown), but located within the housing portion 26 thatdrives a saw blade 28. A handle 30 enables the operator to move theblade and motor assembly 20 into and out of engagement with a workpiece(not shown) that is placed on the table 16 adjacent the fence 14.

The blade and motor assembly 20 is pivotable about a saw pivotconnection shaft 204 extending between a pair of spaced outer flanges206 on a pivot head 208. When the handle 30 is lowered by an operator,the blade 28 will be lowered into its cutting position and slightlypenetrates a slot 210 formed in the table 16. The pivot head 208 alsohas a pair of spaced inner flanges 212 (best shown in FIG. 13) thatextend in the opposite direction from the outer flanges 206 that areconnected to the blade and motor assembly 20, and offset from the centerof the pivot head 208, opposite one of the outer flanges 206. The innerflanges 212 are provided between a pair of spaced outer flanges 218extending from one end of a first horizontal link 214. A pivotconnection shaft 216 extends horizontally through holes in the inner andouter flanges 212 and 218 to pivotally connect the inner and the outerflanges 212, 218. Together the inner flanges 212 of the pivot head 208,the pivot connection shaft 216 and the outer flanges 218 of the firsthorizontal link 214 form a horizontal hinge connection 220.

At the opposite end from the horizontal hinge connection 220, the firsthorizontal link 214 is connected to a slightly longer second horizontallink 222 by another horizontal hinge connection 224. It should beunderstood, however, that the miter saw 200 may include one or moreadditional horizontal links that may be connected to the first andsecond links 214, 222 without departing from the scope of the patent.Included in the hinge connection 224 is a pair of spaced inner flanges226 that extend from the end of the first horizontal link 214 oppositethe end having outer flanges 218. The inner flanges 226 are providedbetween and pivotally connected to a pair of spaced outer flanges 228extending from the upper end portion of the second horizontal link 222,by a pivot connection shaft 230.

The second horizontal link 222 has its lower end portion connected to avertical support 232 by a horizontal hinge connection 234. The hingeconnection 234 includes a pair of spaced outer flanges 236 (best shownin FIG. 15) extending from the top of the vertical support 232 and apair of inner flanges (not shown) extending from the lower end of thehorizontal link 222 and provided between the outer flanges of thevertical support. A pivot connection shaft 238 extends through the outerflanges 236 of the vertical support 232 and the inner flanges of thesecond horizontal link 222 for a pivotal connection. The outer flanges228 of the second horizontal link 222 in the hinge connection 224extends at an angle of approximately 30 degrees from the generallylinear longitudinal portion of the second horizontal link to enable thefirst horizontal link 214 to be folded close to the second horizontallink, as shown in FIG. 14. It is to be understood that the angle otherthan the described above may be utilized as well.

As is best shown in FIGS. 14 and 16, when the blade and motor assembly20 is in its retracted position, the second horizontal link 222 is in agenerally vertical orientation. It should be appreciated that thehorizontal pivot connection shafts 216, 230, 238, and the correspondinghinge connections 220, 224, 234, are oriented parallel to one anotherand substantially perpendicular to the plane of the blade 28. The firstand second horizontal links 214, 222 are relatively wide, approximately80 to 160 millimeters and the thickness of them is substantial,approximately 10 to 80 millimeters so that they resist bending whichwould detrimentally affect the quality of the cut by the blade 28. Thelength of the first horizontal link 214 is approximately ¾ of the lengthof the second horizontal link 222. In one embodiment, the length of thefirst horizontal link 214 is approximately 120 to 220 millimeters andthat of the second horizontal link 222 is approximately 200 to 300millimeters so that the point of the blade 28 that make contact with theworkpiece is at a sufficient distance from the fence 14 to cut theintended workpiece, but before the contact point reaches the end of theslot 210 provided in the table 210. Of course, it should be understoodthat the width, the thickness, and the length of the first and secondlinks 214, 222 other than those described above may be utilized as well.

The vertical support 232 is integrally formed with a support frame 240that is generally cylindrically shaped. Of course, the support frame 240may take the form of various shapes and have a number different sizes. Abevel pivot shaft 242 supported by an extension 244 of the table 16enables the support frame 240 and the vertical support 232 to pivoteither to the left or right of the plane of the blade 28 for the purposeof providing bevel cuts. The vertical support 232 also has a sidemounting structure 246 with a pivot block 248 for pivotally supportingan angled first vertical link 250, which has a pair of outer flanges 252at one end. The pivot block 248 is provided between and connected to thetwo outer flanges 252 of the first vertical link 250 by a vertical pivotconnection shaft 254 that extends through the holes formed in the outerflanges and the pivot block. The outer flanges 252, the pivot block 248and the pivot connection shaft 254 combine to form a vertical hingeconnection 256. It should be noted that the pivot block 248 can be anintegral part of the vertical support 232, or it can be a separatecomponent that is affixed to the vertical support 232.

Referring to FIGS. 13, 15 and 16, the first vertical link 250 has a pairof spaced inner flanges 258 extending from the end opposite the endhaving the outer flanges 252. The inner flanges 258 are provided betweena pair of spaced outer flanges 260 extending from a second vertical link262. A vertical pivot connection shaft 264 extends through the alignedholes in the inner and outer flanges 258, 260 to pivotally connect thefirst and second vertical links 250, 260 together and form a verticalhinge connection 266. While the inner flanges 258 are described as being“spaced,” it should be understood that they are not necessarilyseparated. They can also be integrally connected by a somewhat narrowerpiece provided between the flanges 258. Alternatively, the inner flanges258 can also be replaced with one cylindrical piece protruding from theend of the link 250.

As best shown in FIG. 15, the outer and the inner flanges 260, 258 ofthe second vertical link 262 and the first vertical link 250 extend at aslight angle from the linear portion of each of the first and secondvertical links 250, 262 to enable the first and second vertical links250, 262 to be folded close to each other, as shown in FIG. 16.Preferably, the flanges 258, 260 should extend at an angle ofapproximately 30 to 120 degrees relative to the linear portion of therespective first and second vertical links. It is to be understood thatthe angle other than the described above may be utilized as well.

At the opposite end from the outer flanges 260, a pair of spaced outerflanges 268 extend from the second vertical link 262 and are pivotallyconnected to a pivot block 270 provided between the two outer flanges bya vertically oriented pivot connection shaft 272 (best shown in FIGS. 13and 14), thereby forming another vertical hinge connection 274. Thepivot block 270 is attached to the pivot head 208 on the opposite sidefrom the outer flanges 206 and adjacent the inner flanges 212 of thepivot head.

As with the embodiment shown in FIG. 13, the vertical pivot connectionshafts 254, 264, 272 maintain the elevation of the pivot head 206substantially constant relative to the table 16. The length of the firstvertical link 250 is approximately the same as the length of the secondvertical link 262, and each of the first and second vertical links 250,262 are approximately 7/10 of the length of the second horizontal link222. In one embodiment, the length of the first vertical link 250 isapproximately 120 to 220 millimeters and that of the second verticallink 262 is also approximately 120 to 220 millimeters. The width andthickness of the first and second vertical links 250, 262 are comparableto the first and second horizontal links 214, 222. However, the amountof possible bending of the vertical links 250, 262 is not as critical asbending that could occur with the horizontal links 214, 222 inasmuch asthe quality of a cut is generally not affected by vertical movement ofthe blade during extension and retraction because the blade penetratesthe slot 210 during most cutting operations. Of course, it is to beunderstood that the width, the thickness, and the length of the firstand second links 214, 222 other than those described above may beutilized as well. As is evident from the drawings, the horizontal andvertical links 214, 222, 250, 262 are not solid but may be constructedfrom cast of aluminum and have reinforcing ribs 276 (best shown in FIG.14) that extend across the interior of the links to impart additionalstrength. In some embodiments, the horizontal and vertical links 214,222, 250, 262 may be constructed from steel stamping, sheet metal, orany high strength plastic.

Additional structural strength is provided in this embodiment for thereason that all the horizontal and the vertical hinge connections 220224, 234, 256, 266, 274 have outer flanges that fit outside a pair ofinner flanges or pivot blocks, which support each the horizontal andvertical links 214, 222, 250, 262 at both ends rather than an overhungload connection. The double-ended support provides a stronger connectionthat imparts an increased strength to the links. The horizontal andvertical pivot connection shafts 216, 230, 238, 254, 264, 272 are,therefore, also supported at opposite ends, which is a strongerconnection.

In the described fourth embodiment, the vertical hinge connection 256 atthe lower end of the first vertical link 250 is provided at the topportion of the vertical support 232 (not including the outer flanges236) and is slightly below the vertical hinge connection 266 at theother end of the vertical link 250 (best shown in FIG. 14). Accordingly,the vertical link 250 extends at an angle between the vertical hingeconnections 256 and 266. It should be understood, however, that thelength of the vertical support 232 may be increased so that the locationof the pivot block 248, and accordingly, the vertical hinge connection256, may be at the same height as the vertical hinge connection 266. Inother words, the first vertical link 250 may extend substantiallyparallel to the table top 16 as is the second vertical link 262.However, with this arrangement, there may be an issue of the miter saw200 being undesirably top heavy.

Another consideration is that the angle between the first and secondhorizontal links 214, 222 as determined by the line of action between aline extending through pivot connection shafts 230 and 216 in thehorizontal hinge connections 224 and 220 relative to the line of actionthrough pivot connection shafts 230 and 238 in the horizontal hingeconnections 224 and 234, identified as angle θ₁ in FIG. 15 should beless than 130° when the saw is fully extended to prevent a toggle actionof the links. While not shown, the angle between the first and secondvertical links 250 and 262 as determined by the line of action between aline extending through vertically oriented pivot connection shafts 264and 254 in the vertical hinge connections 266 and 256 relative to theline of action through vertical pivot connection shafts 264 and 272 inthe vertical hinge connections 266 and 274, also should be less than130° when the saw is fully extended to prevent a toggle action of thelinks. The toggle action is defined herein to mean an increasednecessary force to push the blade and motor assembly 20 from itsextended position, shown in FIGS. 13 and 15 toward the retractedposition shown in FIGS. 14 and 16. If a toggle action is experienced, agreater noticeable and appreciable force is required to start themovement. If the angles of the links are less than 130°, such toggleaction is not experienced.

During operation, an operator places a workpiece on the table 16, bringsthe handle 30 down into cutting position either before or afteractivating the motor 24, as shown in FIGS. 13 and 15, and then pushesthe handle 30 toward the fence 14 to have the blade 28 cut theworkpiece. At the end of the cut, the blade and motor assembly 20 wouldbe essentially in the position shown in FIGS. 14 and 16, where thebottom reach of the blade 28 is generally coextensive with the fence 14.

As is shown in FIGS. 15 and 16, the first and second vertical links 250,262 are located beneath the first and second horizontal links 214, 222and the vertical connection hinge 266 that interconnects the verticallinks extends away or to the left side of the saw (as viewed from thehandle 30). In this manner, when the saw 200 is in a retracted positionand the vertical and horizontal links 214, 222, 250, 262 are foldedtogether, as shown in FIGS. 16-19 only a small portion (e.g.,approximately 20 to 100 millimeters) of the vertical links 250, 262extend outside of the width of the horizontal links 214, 222. This issignificant in that changing of the bevel angle of the blade and motorassembly 20 can be accomplished in either the left or right directionand the vertical links 250, 262 will not interfere with the dual beveladjusting capability, as illustrated in FIG. 19.

Another desirable attribute of this described embodiment is particularlyillustrated in FIGS. 14, 16 and 17 wherein the blade and motor assembly20 is in its retracted position and the second horizontal link 214 issubstantially vertical. Since the link 214 does not extend rearwardlybeyond the vertical support 232, it can be appreciated that the saw 200can be placed very close to a rear wall or the like without impairingthe normal operation of the saw.

In accordance with another aspect of the invention, the miter saw 200includes a locking mechanism, indicated generally at 278, for lockingthe saw blade and motor assembly 20 in a fully retracted position (seeFIG. 16) or a fully extended position (see FIG. 15). During transport,the blade and motor assembly 20 may undesirably move from one positionto another which can make the saw more cumbersome, or even hazardous, tocarry. The locking mechanism 278 locks the saw blade and motor assembly20 in the fully extended position so that the saw 200 is easier tocarry. Also, when making chop cuts where the blade 28 is brought downonto the workpiece without sliding the saw blade and motor assembly 20to an extended position, the locking mechanism 278 locks the saw bladeand motor assembly 20 in the fully retracted position.

Referring to FIGS. 20 and 21, the locking mechanism 278 includes pivotfoot 280, a generally flat, horizontally oriented locking lever 282extending from the foot in one direction, and a generally flat,vertically oriented wedge 284 extending from the foot in the oppositedirection of the locking lever. The foot 280 is pivotally connected to apair of spaced support arms 286 which protrude from the top one of theinner flanges 258 on the first vertical link 250 by a pin 288 (bestshown in FIGS. 24 and 25). The pin 288 extends through a hole in each ofthe arms 286 and an aligned hole formed in the foot 280. The pin 288 issecured in the hole by any know means such as a threaded nut or aretaining ring, for example.

The locking mechanism 278 also includes a generally flat spring 290(best shown in FIGS. 20, 21, 25 and 26), one end of which is fixed tothe flange 258 between the two support arms 286. The spring can beattached to the flange 258 by welding, screws or otherwise affixed tothe flange in any known manner. The spring 290 can also be secured bywrapping the end around the pin 288. The spring 290 is configured to becurved upwardly to aU shape as shown in FIGS. 20 and 21. Preferably, thespring 290 is made of metal so that it biases against force pressing onit and has the resiliency to go back to its predefined shape. However,plastic or other suitable material with sufficient resiliency may alsobe utilized for the spring 290.

The spring 290 serves to maintain the locking mechanism 278 in itscurrent position, whether in a locked position, as shown in FIG. 20 orin an unlocked position, as shown in FIG. 21. When in the lockedposition, the spring 290 biases against a lip 292 protruding from thefoot 280 to urge the lever 282 and the wedge 284 or in a clockwisedirection to a horizontal position. In this position, the wedge 284 isplaced in an elongated locking slot 294 created between the top innerflange 258 of the first vertical link 250 and the top outer flange 260of the second vertical link 262 (best shown in FIGS. 24 and 27). In theunlocked position, the spring 290 is biased against the front of thefoot 280 between the lip 292 and the locking lever 282 to maintain thelever 284 and the wedge 284 in an angled position, so that the wedge 284is kept out of the locking slot 294. The locked and unlocked positionscan be at both the fully retracted position (FIGS. 25 and 24,respectively) and in the fully extended position (FIGS. 26 and 27,respectively).

The flanges 258 extend from the end of the first vertical link 250,thereby defining a pair of shoulders 296 with a flat surface 298 (bestshown in FIG. 21). The surface 298 is at an angle of approximately 150degrees relative to the straight longitudinal section of the firstvertical link 250 extending between the hinge connections 266 and 248(best shown in FIG. 22). As shown in FIG. 22, the outer flanges 260 ofthe second vertical link 262 each has a flat inside surface 300 facingand spaced from the shoulder surfaces 298 of the vertical link 250. Whenthe blade and motor assembly 20 is moved to the fully retractedposition, the opposing shoulder surface 298 and the inside surface 300of the second vertical links 262 are spaced parallel to each other anddefine the locking slot 294. Accordingly, the outer flanges 260 extendat an approximately 150 degree angle relative to the straightlongitudinal section of the second vertical link 250 extending betweenthe hinge connections 266 and 274, so that the inside surface 300 isparallel to the shoulder surface 298 of the first vertical link 250.

The outer flanges 260 also have a generally flat end surface 302 whichextends away from the inside surface 300 at an angle slightly less than90 degree. When the blade and motor assembly 20 is moved to the fullyextended position, the end surface 302 of the outer flanges 260 and theopposing shoulder surface 298 are spaced parallel to each other anddefine the locking slot 294, as shown FIG. 23.

As shown in FIGS. 22 and 23, in the locked position, the wedge 284displaces almost the entire space within the locking slot 294. As aresult, the outer flanges 260 of the second vertical link 262 and theinner flanges 258 of the first vertical link 250 are prevented frompivoting relative to each other. In other words, the locking mechanism278 makes the vertical hinge connection 266 connecting the first andsecond vertical links 260, 262 inoperable. Moreover, the lockingmechanism 278 can be put into the locking position only from the fullyextended or fully retracted positions. At any place in between these twopositions, the locking slot 294 does not have the opposing surfaces 298and 302 that are parallel, and therefore, the locking slot 294 would betoo narrow and incapable of receiving the wedge 284.

In operation, to lock the blade and motor assembly 20, the user movesthe blade and motor assembly to either the fully retracted position(FIG. 23) or the fully extended position (FIG. 26), so that the lockingslot 294 is formed between the opposing shoulder surface 298 of thefirst vertical link 250 and the inside surface 302 of the outer flanges(if fully retracted) or between the shoulder surface 298 and the endsurface 302 of the outer flanges 260 (if fully extended). The lockinglever 282 is then lifted upwardly to cause the foot 280 to pivot aboutthe pin 288 and bring the wedge 284 into the locking slot 294 (see FIG.20). The wedge 284 is maintained in the locking slot 294 by the tensionon the free end of the spring 290 acting against the lip 292 in aclockwise direction.

To unlock the blade and motor assembly 20, the user pushes the lockinglever 282 downwardly to overcome the force acting on the lip 292 of thefoot 280 and causes the foot to pivot counterclockwise about the pin 288and bring the wedge 284 completely out of the locking slot 294 (see FIG.21). In the unlocked position, the free end of the spring 290 ispositioned on the front of the foot 280, between the lip 292 and thelocking lever 282. The force of the spring acting on the front of thefoot 280 keeps the locking mechanism 278 in the unlocked position, sothat the user is able to slide the blade and motor assembly 20 asdesired.

While various embodiments of the invention have been shown anddescribed, it should be understood that other modifications,substitutions and alternatives are apparent to one of ordinary skill inthe art. Such modifications, substitutions and alternatives can be madewithout departing from the spirit and scope of the invention, whichshould be determined from the appended claims.

Various features of the invention are set forth in the following claims.

What is claimed is:
 1. A power saw comprising: a table configured to receive a workpiece; a saw blade and motor assembly; a linear guide mechanism operatively connected to said table and being configured to pivotally support said saw blade and motor assembly, said linear guide mechanism enabling movement of said saw blade and motor assembly along a predetermined linear path in a forward or a rearward direction at a constant level; said linear guide mechanism including a first link and a second link pivotally connected by a first hinge connection, said first and second links enabling said linear guide mechanism to maintain said saw blade and motor assembly at said constant level; and a locking mechanism fixed to said first hinge connection for locking said linear guide mechanism to prevent said saw blade and motor assembly from being moved along said predetermined linear path, wherein said locking mechanism includes an elongated wedge portion configured to be pivotally inserted in a space created between opposing ends of said first and second links at said first hinge connection, to prevent said first and second links from pivoting about said first hinge connection relative to each other.
 2. The power saw as defined in claim 1, wherein said locking mechanism locks said linear guide mechanism in a retracted position in said rearward direction or in an extended position in said forward direction.
 3. The power saw as defined in claim 1, wherein said locking mechanism further includes a pivot foot from which said wedge portion extends, and a locking lever extending from said pivot foot for operatively pivoting said wedge portion about said pivot foot to insert or extract said wedge portion in and from said space between said opposing ends of said first and second links.
 4. The power saw as defined in claim 3, wherein said locking mechanism further includes a spring member for biasing said pivot foot at a first position to retain said wedge portion in said space between said opposing ends of said first and second links, or at a second position to maintain said wedge portion outside of said space.
 5. The power saw as defined in claim 4, wherein said pivot foot has a lip protruding at said first position and said spring member biases against an end of said lip to retain said wedge portion in said space between said opposing ends of said first and second links, and said second position is provided between said lip and said locking lever.
 6. The power saw as defined in claim 3, wherein said pivot foot pivots about a pin supported between a pair of spaced arms protruding from said first hinge connection.
 7. The power saw as defined in claim 1, wherein said space between said opposing ends of said first and second links is configured to receive said wedge portion at least one predefined angle between said first and said second links.
 8. The power saw as defined in claim 7, wherein said opposing ends of said first and second links are angled such that a shape of said space corresponds to a shape of said wedge portion at said at least one predefined angle between said first and said second links.
 9. The power saw as defined in claim 8, wherein said shape of said space corresponds to said shape of said wedge portion at said at least two predefined angles between said first and said second links.
 10. A locking mechanism in a power saw for locking a linear guide mechanism that supports a saw blade and motor assembly and enables movement of said saw blade and motor assembly along a predetermined linear path in a forward or a rearward direction at a constant level, said locking mechanism comprising: a pivot foot pivotally attached to a first hinge connection connecting a first link and a second link of said linear guide mechanism, said first and said second links enabling said linear guide mechanism to maintain said saw blade and motor assembly at a constant level; an elongated wedge portion extending from said pivot foot and configured to be pivotally inserted in a space created between opposing ends of said first and second links; and a locking lever extending from said pivot foot for operatively pivoting said wedge portion about said pivot foot to insert or extract said wedge portion in and from said space between said opposing ends of said first and second links; wherein said wedge portion prevents said first and second links from pivoting about said first hinge connection relative to each other when said wedge portion is inserted in said space between said opposing ends of said first and second links.
 11. The locking mechanism as defined in claim 10, further comprising a spring member for biasing said pivot foot at a first position to retain said wedge portion in said space between said opposing ends of said first and second links, or at a second position to maintain said wedge portion outside of said space.
 12. The locking mechanism as defined in claim 11, wherein said pivot foot has a lip protruding at said first position and said spring member biases against an end of said lip to retain said wedge portion in said space between said opposing ends of said first and second links, and said second position is provided between said lip and said locking lever.
 13. The locking mechanism as defined in claim 10, wherein said pivot foot pivots about a pin supported between a pair of spaced arms protruding from said first hinge connection.
 14. The power saw as defined in claim 10, wherein said space between said opposing ends of said first and second links is configured to receive said wedge portion at least one predefined angle between said first and said second links.
 15. The power saw as defined in claim 14, wherein said opposing ends of said first and second links are angled such that a shape of said space corresponds to a shape of said wedge portion at said at least one predefined angle between said first and said second links.
 16. A power miter saw having a locking mechanism, comprising: a rotatable table configured to receive a workpiece; a pivotable saw blade and motor assembly including a motor for rotating a circular saw blade; a linear guide mechanism operatively connected to said table and being configured to pivotally support said saw blade and motor assembly, said linear guide mechanism enabling movement of said saw blade and motor assembly along a predetermined linear path in a forward or a rearward direction at a constant level; said linear guide mechanism including a first link and a second link pivotally connected by a first hinge connection, said first and second links enabling said linear guide mechanism to maintain said saw blade and motor assembly at said constant level; a pivot foot pivotally attached to a first hinge connection pivotally connecting a first link and a second link of said linear guide mechanism, said first and second links enabling said linear guide mechanism to maintain said saw blade and motor assembly at a constant level; an elongated wedge portion extending from said pivot foot and configured to be pivotally inserted in a space created between opposing ends of said first and second links; and a locking lever extending from said pivot foot for operatively pivoting said wedge portion about said pivot foot to insert or extract said wedge portion in and from said space between said opposing ends of said first and second links; wherein said wedge portion prevents said first and second links from pivoting about said first hinge connection relative to each other when said wedge portion is inserted in said space between said opposing ends of said first and second links.
 17. The locking mechanism as defined in claim 16, further comprising a spring member for biasing said pivot foot at a first position to retain said wedge portion in said space between said opposing ends of said first and second links, or at a second position to maintain said wedge portion out of said space.
 18. The power saw as defined in claim 16, wherein said opposing ends of said first and second links are angled such that a shape of said space corresponds to a shape of said wedge portion at least one predefined angle between said first and said second links.
 19. The power saw as defined in claim 18, wherein said shape of said space corresponds to said shape of said wedge portion at a first predefined angle near an end of said forward direction movement of said saw blade and motor assembly, and at a second predefined angle near an end of said rearward direction movement of said saw blade and motor assembly. 